Chapter 1: Earth Systems Flashcards
What is the scientific method?
The experimental environment is often the earth, and not a laboratory.
Kola hole near St. Petersburg, Russia.
12.262 km deep.
Deepest physical measurement on earth is only 12 km down.
Scientify Theory
Should stand the test of time
Is not just a guess.
May be the ultimate conclusion, unless necessary control experiments can be made that would ultimately prove/disprove the process
EX: Einstein’s theory of relativity is necessary for your GPS to accurately locate your car.
Emphirical Generalization
A statement of a biological principle that appears to be without exception at the time it is made, and has become consolidated by repeated successful testing; rule.
Law of Uniformitarianism
Processes on Earth today have worked much the same way throughout geologic history (James Hutton, 1785).
“The present is the key to the past” Charles Lyell, 1830
Not all events are gradual. Some are rare but extreme. EX: Super eruptions, meteor impacts, ice ages
Geodesy
One of the oldest branches of geology, that originally aimed to determine the shape and size of the earth.
Evidence for a round earth:
- Lunar eclipse (earth’s shadow is circular)
- Ships disappearing in the distance
Eratosthenes (Greek ~30 BC)
Made the first accurate estimate of the size of the earth.
Measured the deflection of the sun in two cities (one near the tropic of Cancer during the summer solstice, the other about 800 km north).
A little geometry, and he found a solution within 10% of the modern known radius (6371 km).
Is the Earth perfectly round?
Not quite, but almost.
Gravity works to keep the sphere perfect, but active forces drive mountains to rise high and make trenches deep.
Mount Everest = 8850 m above sea level
Challenger Deep off Marianas = > 11,000 m deep
How much do peaks and troughs change the shape of the Earth?
|max elevation| / earth diameter
11,000 m /13,000,000 m = 0.00085
= 0.085 %
What is the furthest point from the center of the earth?
Volcan Chimborazo in Ecuador at 6,384.3 km from the center of the earth.
Because of the Earth’s rotation, centrifual forces act to pull the equator out and flatten the poles.
How do we really know what Earth’s Interior looks like?
Rock sampling & drilling (12.3 km max)
Meteorites
Seismic Studies
What type of rock does rock sampling enable us to see?
What is the average density of this rock?
We only see crustal rocks this way.
Avg crustal rock is granitic density :
r ~2,800 kg/m3 (2.8 g/cm3),
however, because earth’s gravity (g = 9.8 m/s3), avg earth density =
r ~5,500 g/cm3
What are the types of seismic waves?
P- and S-waves can reflect and/or refract across a variety of Earth’s internal boundaries
Label
Earth consists of a series of concentric layers (spheres). What are the two categories by which they are define?
Chemical and Mechanical.
What are the earth’s three integrated systems, their sub-components, and their purposes?
The Climate System: involves interactions among:
- Atmosphere- gaseous envelope from earth’s surface to altitude of 100 km
- Hydrosphere- all surface and ground waters
- Biosphere- all organic matter related to life on earth’s surface
The Plate Techtonic System involves interactions among:
- Lithosphere (also in climate system)- strong, rocky outer shell of solid Earth crust and uppermost mantle
- Asthenosphere: weak, ductile later of mantle
- Deep mantle- beneath asthenosphere
The Geodynamo System
- Inner core- mostly solid iron
- Outer core- mostly molten iron
For what percentage of geologic time have vertebrates been around?
Human civilization?
Vertebretes for 10% earth history.
Human civilization: 0.0001% earth history.
